EXPERT! REBUILD a Briggs and Stratton Lawnmower AUTOMATIC CHOKE CARBURETOR

good morning today I'm going to teach you how to rebuild a carburetor on a Briggs and Stratton engine it's a quantum style engine it's a six point seven five horsepower but most of the carburetors are all the same so the first thing you want to do is drain the gas out however you can do that safely the tools you will need to remove the carburetor for rebuilding are a you'll need a 5/16 socket or whatever and a 3/8 and to make your life easier I always prepare these around two so basically what you want to do to remove the carburetor is take off the air filter and you have three bolts that mount the air filter housing to the carburetor these two here basically mount directly to the carburetor and this just mounts to a little bracket once you have those three out you will be able to remove this it just pops right out you can see this is the crankcase breather hose you want to make sure that you reconnect it when you reassemble it looks like I'm also going to need a Phillips head screwdriver and a quarter inch wrench because I'll have to take this housing off to get to this a little mounting bolt here for the choke good takeoff top cover here it's just two Phillips heads usually move that aside zoom in here a little bit and this is the one I'll be removing next have to be really careful with this mechanism here after you remove this bolt it's real easy to displace this mechanism here on the inside where it attaches over here so just be very careful when you take it loose not to to jar it too much [Music] there's a little spring here so be careful that doesn't go flying really important when you retighten this to put it back together that you don't over tighten it it's really easy to strip out housing here all right so we're loose there what I always do before I remove loosen the carburetor go ahead and take off the hose clamp and remove the fuel hose guys say I did drain the gas before I got started here so hopefully there's none in there now let me show you some of the corrosion here on this fuel Inlet we all that gross stuff [Music] anyways you can see one of the carburetor mount bolts you have two of them there's one back in there and then one on the other side and that's the 3/8 socket that you'll be using for that be careful working in the gravel here I always lose my stuff move this three-eighths we remove this three-eighths and there is a linkage we're going down to take out and as with most most carburetors you pull it out and you rotate the carburetor and it comes right off all right so you'll go ahead and pull the carburetor free and you can see how the linkage you just kind of rotate the carburetor you can see that on the camera it slides right off this is actually the auto choke mechanism so this engine doesn't have a primer you have to worry about it automatically adjusts the choke depending on the temperature of the engine it's pretty slick there's also a little o-ring on here that you need to be cautious of that it remains on there when you reassemble things it's usually in good condition I rarely have to replace them but you can see it on there you're right there on the intake you have that o-ring so you want to make sure that stays on there also a good time to inspect the fuel line just replace it that's usually the best thing to do if I don't have any and not really in a pinch I'll just go ahead and clean out the inside of it all the sediment seems to accumulate right down here on the end let you clean that out real good flush it and you should be okay but it's always a good idea to replace the fuel line if you can okay so to start cleaning and rebuilding this carburetor first thing I always do is remove the float pin as well as the float and the float valve which should be attached to it it's kind of stuck in there you can see there's a lot of varnishing in this carburetor doesn't even want to come out be gentle because that is a plastic float and pry up on it a little bit here might have to soak this carburetor first although I do see it's coming up that each that's nasty in there okay got it out it's in pretty bad shape but I think we can clean it up so before I soaked this carburetor there's a couple of things that a lot of folks overlook there is a seat down in this whole little rubber seat that needs to be removed and replaced with a new one whenever you would build a carburetor I'm also going to use this little pic here to remove that needle seat as well as help take off the local oring which we will discard so basically which you just got to be very careful down in there when removing that seat to not scratch the body of the carburetor but get in there so you can pull that little rubber piece out sometimes it comes out in pieces and it's usually red and color or green you'll see when it comes out there we go and there we are in really bad shape so we'll replace that I'm going to go ahead and scrape off some of this corrosion and we're going to soak this carburetor overnight when you're rebuilding a quantum carburetor these are pretty much the parts that you're going to replace most commonly the float Bowl will ring the seat and the float needle this is the needle and seat that I'll be putting in there as well as a new float bolt so I'm going to soak this carburetor and all the components and coke sometimes it works to help get all that crud off there sometimes it doesn't but I always like to use try using this first before I go to the harsh chemicals so sometimes I'm really impressed with how coca-cola cleans dirty carburetors I don't know if you can see but what an improvement and most of that is just from soaking in coca-cola for a few hours and scrubbing with scrub brushes but we're darn near spotless so even after soaking these carburetors you can still get some crud that refuses to come out use all kinds of tools to clean it out q-tips brass brushes but this is one of my favorites it's basically just wire and I separate the strands and I'm able to use that to poke down into these small holes and clean everything out [Applause] sometimes it takes a few times [Applause] and you may even reinstall this and hook up the carburetor and mower runs for a minute or two and then dies and oftentimes what happens is there's a piece of crud down on the inside of this main jet and it dislodges and plugs up the main jet hole and something the size of a speck of sand can plug up the main jet and prevent this carburetor from running and we will rinse thoroughly with carburetor cleaner as well to get all the coke coca-cola residue off there of course so this is the easiest way I've found to do this remember we have to replace the carburetor seat which is where this q-tip is I'm making sure it's good and cleaned out now when you install the seat we want to make sure that you install it I don't know if you can see it but there's a little groove there and you want to install it groove side down let's see can you see it maybe maybe not anyways so what I always do is I spray a little bit of wd-40 down in there just to make sure the seat slides down in you stick that in there just enough to get it in there straight with the grooves down and then I just use a little punch and I push this all the way down and seat it see that down in there make sure that seats down all the way you don't have to push it real hard but enough to make sure it's seated all right now we're ready for the new float valve which is right here and the float okay so I have the float here with the new float valve attached right there and the hinge pin you're going to go ahead and reassemble just like we took it apart put the hinge pin in and all right we have a working carburetor again the brass brush is the thing to use for cleaning out all the carburetor parts it won't gauge the metal so when you're putting the float Bowl gasket back on just want to mention there is two different types there's a thicker one and a thinner one and you can see the one that's all dirty the one that came off fit is actually the thicker one so we will make sure to replace it with the thicker one now be careful not to over-tighten this this is a brass nut or a bat bolt going into an aluminum carburetor so be very careful not too tight all right let's go ahead and get this thing back together I'm going to make some important points as I'm going back together here - so once again make sure that the o-ring is still on the intake let's go ahead and put it on the throttle linkage so remember we're going to turn the carburetor this way put it on and rotate that will get it on the linkage all right make sure it's not bound up looks good let's go ahead and mount the auto choke mechanism here and you want to make sure that the pin on the auto choke mechanism goes down through the slot on your choke here on the carburetor and you can just finger tight that for now you're going to want to get your 3/8 bolts right here to that mount the carburetor on just two of them all right the other 3/8 and I kind of go back and forth tightening them up not too tight all right I still need to tighten up the auto choke but it looks like it's functioning correctly and the throttle linkage is also functioning correctly if not it's not bound up or anything go ahead and put the fuel line on get my pliers for the clamp and you must be very careful when tightening this down because it's it's a small quarter-inch and you can very easily strip out the aluminum that threads into one thing to mention on the back of the carburetor on the air filter mounting plate there is a gasket it's not as important with the auto choke but if this was a push-button primer style setup you definitely need to replace this gasket but I'm not going to do that today with this Auto choke unit alright just like it put that this back on just like it came off usually tighten up the the two screws that go directly into the carburetor first you'll want to install them all before you start tightening down that's 5/16 make sure we're square on there alright so after I tighten up these three I recheck my linkages make sure everything's still functioning correctly there and we're ready for the air filter all right this baby is ready to test out I'm going to remove this little cover makes my life easier okay not too tight because it is plastic you're screwing into just snug it'll stay so I'm going to give you some top-secret information right now so most lawnmowers have a throttle spring governor control spring if your lawn mower doesn't rev up very well or you need more power you may need to adjust the spring right here and this bracket to increase the Rev of the lawnmower all you need to do is bend this bracket that way a little bit I mean just a little bit and it will increase the RPMs of the lawnmower tech tip of the day all right let's test it out you

Channel: Jeff's Little Engine Service

Views: 343,970

Rating: 4.7905669 out of 5

Keywords: float bowl, carb, carberator, carbuerator, briggs, fix, bad gas, rebuild, lawnmower, lawn mower, tune up, craftsman, fuel, ethanol, carb., my, run, problem, how to, tank, gas, start, fuel problem, no gas, troubleshoot, wont, won't, will not, common, small engine, stay running, surges, dies, brigs, yourself, problems, auto choke, automatic choke, horsepower, gasket, walbro, keihen, spring, placement, where, go, does, choke, auto, automatic, carburetor, stratton, straten, how, lever, diagram

Id: qXp5ii_RerA

Length: 17min 53sec (1073 seconds)

Published: Wed Aug 26 2015